Joerg, Glenn
I've played with NAV Alt Speed PIDs and found that to increase altitude vertical speed you need to increase the Nav Alt speed OM.
Increasing Nav Alt Speed P and PM seems to increase vertical acceleration from hover to max vertical speed.
Be ready to switch to manual because things can change fast when you make too big of a change in these settings.
Reading the wiki gave me some idea of how all these PIDs are supposed to work.
http://autoquad.org/wiki/wiki/flying/tu ... on-tuning/
Larry